1. Field of the Invention
The present application is a divisional of application Ser. No. 09/619,314 filed on Jul. 19, 2000, now U.S. Pat. No. 6,475,279. The present application relates to a substrate processing apparatus and a substrate processing method each for applying a coating solution to a substrate such as a semiconductor wafer and the like and performing heat processing and subsequent cooling processing for the substrate.
2. Description of the Related Art
In a photolithography process of a semiconductor device, a semiconductor wafer is coated with a resist, a resist film formed by the coating is exposed in accordance with a predetermined circuit pattern, and the exposed pattern is developed, whereby a circuit pattern is formed on the resist film.
To perform such a series of processes, a resist coating and developing processing system has been conventionally used. The resist coating and developing processing system is so structured that a processing station in which various kinds of processing units for performing various kinds of processing for coating and developing on the semiconductor wafer are multi-tiered, a cassette station, in which cassettes for housing a plurality of semiconductor wafers are mounted, for carrying the semiconductor wafers into the processing station one by one and carrying a semiconductor wafer after processing out of the processing station and housing it in a cassette, and an interface section for receiving and passing the semiconductor wafer from/to an aligner, provided adjacent to the system, for exposing a resist film in a predetermined pattern, are integrally provided.
In such a resist coating and developing processing system, for example, wafers are taken out of the cassette placed in the cassette station one by one and transferred to the processing station. After the wafer is first brought to a predetermined temperature in a cooling unit, a reflection prevention film (a bottom layer) is formed in a resist coating unit, and the wafer is subjected to heat processing in a hot plate unit (a heat processing unit) and cooled in a cooling unit (a cooling processing unit). Then, the wafer is coated with a photo resist film in a resist coating unit and subjected to baking processing in a heat processing unit.
Thereafter, the semiconductor wafer is transferred to the aligner from the processing station via the interface section, and the resist film is exposed in a predetermined pattern in the aligner. After the exposure, the semiconductor wafer is transferred again to the processing station via the interface section. First, the exposed semiconductor wafer is subjected to post-exposure bake processing in the hot plate unit, and coated with a developing solution in the developing unit after cooling, whereby the exposed pattern is developed. Thereafter, the wafer is subjected to postbake processing in the hot plate unit and cooled, thereby completing a series of processes. After the completion of the series of the processes, the semiconductor wafer is transferred to the cassette station and housed in a wafer cassette. Such processes are repeated successively for a predetermined number of semiconductor wafers one by one.
In such a series of resist coating and developing processing, as described above, heat processing is performed in the hot plate unit prior to the resist coating and the developing solution coating. However, since the resist coating and the developing solution coating are carried out in a temperature-adjusted atmosphere, the semiconductor wafer after the heat processing needs to be cooled in the cooling unit and controlled to a predetermined temperature.
By the way, in recent years, a demand for micromachining of a semiconductor device has been increased, and hence a high sensitive type resist solution is used. Accordingly, it is necessary to manage an atmosphere temperature in the resist coating with high accuracy.
Therefore, it is required to control a substrate temperature with high accuracy in the cooling unit before the substrate is carried into the resist coating unit. Further, temperature control with high accuracy is required also in the developing unit though the control is not so high in accuracy as that in the resist coating unit.
However, in the above-described resist coating and developing processing system, for the reason that semiconductor wafers are successively processed one by one at a high speed, many hot plate units and cooling units are mounted. Since the semiconductor wafers are transferred to the resist coating units from many cooling units, it is necessary to make these all cooling units temperature-controllable higher in accuracy than conventional ones in order to realize the temperature control with high accuracy in the cooling units, resulting in increased apparatus cost. On the other hand, if the number of the cooling units is reduced to avoid such an inconvenience, the cooling processing is delayed, which causes reduction in throughput.